Re: Integration with infinite upper and/or lower bound

Apart from Werner's correct remarks, the difference is most probably due to an overflow during the numeric integration. This overflow does not occur in the range from 10 to 1000 nm, but somewhere in the vast range between 1000 nm and infinity...

Try to evaluate your integrals (which, by the way are NOT functions of D) symbolically and see what happens.

Producing a 0 answer as a result of this is bad. I'd consider it a bug.

Re: Integration with infinite upper and/or lower bound

The D range is not the problem.

As I had shown with the screenshot from real Mathcad the problem seems to be that the wrong algorithm is automatically chosen (you cannot chose it manually in Prime) if the upper limit is not infinity but infinity times unit nm.